This invention relates generally to a system for introducing natural gas or other gaseous fuel into a gas turbine engine combustor and more particularly to a system that provides a well distributed relatively "lean" mixture of gas and air to the combustor of a gas turbine engine so as to minimize undesirable exhaust emissions. A gas turbine using the system of the invention exhibits very low levels of nitrogen oxide, unburned hydrocarbon and carbon monoxide.
It is well known that oxides of nitrogen form rapidly if high temperatures are reached in the combustion process. Moreover, the level of nitrogen oxide increases as a function of time if the high temperature is maintained. However, the level of nitrogen oxide can be reduced by the entry of dilution air. It is also known to reduce the level of pollutants by reducing the air-fuel ratio to a "lean pre-mixed" fuel-air ratio prior to combustion.